Newly presented study results indicate that using an insertable cardiac monitor can identify Atrial Fibrillation in many patients in whom the current standard of care missed the condition. The study offers hope that stroke risk from Atrial Fibrillation could be reduced from its current level.

Background

Each year in the United States, 795,000 people suffer a stroke, and it is estimated that 25 to 40 percent of those strokes are cryptogenic in nature, meaning they are of unknown cause.

Patients with Atrial Fibrillation(AF) are widely believed to be five times more likely to have a stroke, so the logic goes, that if new monitoring techniques can do a better job of picking up AF, more patients at risk of stroke can be caught early and therapeutic measures taken.

One problem lies in the fact that the condition can be asymptomatic, leaving detection dependent on a host of diagnostic tests that often miss the occurrence of the AF, the paroxysmal nature of it dodging the best efforts of cardiologists to pick it up on snapshot ECG or even 24 hour Holter-type monitoring.

Medtronic’s solution lies in the Reveal® XT Insertable Cardiac Monitor (ICM) and now study results presented at the American Stroke Association conference have confirmed that the device picked up 6.4 times more patients than standard care at six months (p=0.0006).

In addition, the so-called CRYSTAL AF (CRYptogenic STroke And underLying Atrial Fibrillation) Clinical Trial found that compared to standard care (including electrocardiograms, Holter monitors and other short-term diagnostic tests prescribed over the follow-up period), the Reveal ICM detected AF in 7.3 times more patients at 12 months (p<0.0001), and 8.8 times more patients at 36 months (p<0.0001). When followed for 36 months, 30 percent of the patients in the ICM arm had AF detected.

What’s really interesting is that 79 percent of the first AF episodes detected had no symptoms. This means AF likely would have gone undetected by standard care due to patients’ inability to notice warning signs of this dangerous arrhythmia.

Investigator comments

“These study results should make us reconsider how we approach cryptogenic stroke patients. Compared to standard care, continuous monitoring is superior when attempting to diagnose AF in this at-risk patient population, and ICMs offer these patients new hope,” said Richard A. Bernstein, M.D., professor of neurology in the Davee Department of Neurology at Northwestern University and director of the Stroke Program at Northwestern Memorial Hospital in Chicago, and member of the CRYSTAL AF steering committee. “We know patients with cryptogenic stroke are at an increased risk for a subsequent stroke, and finding AF allows us to put patients on medication that should be more effective at preventing these second strokes.”

“As AF is often intermittent and asymptomatic, we can’t rely on symptoms to decide who has AF or who needs monitoring. Continuous monitoring allows us to find the AF that short-term monitoring misses because significant amounts of time can pass between episodes,” said Bernstein.